1. Field of the Invention
The present invention is directed to power consumption optimization circuitry for a system having multiple electronic components of which at least one is always powered on and at least one is normally powered off until otherwise powered on to perform a specific task or function. In particular, the invention is directed to a system including multiple processors of which at least one processor remains continuously powered on at all times, whereas at least one other processor is only powered on in response to a request to perform a specific task or function by that device.
2. Description of Related Art
When power consumption is not a design consideration or factor, a single processor may be used to perform different tasks of varying complexity. As a general rule, the more complex the task or function to be performed by the processor, the higher the clock speed needed. Therefore, when utilizing a single processor the clock frequency selected is the highest frequency necessary for performing the most complex task. This design configuration is advantageous in that it requires less components and thus a smaller footprint, but disadvantageously requires that the processor operate continuously at the highest clock speed for performing the most complex task. The most complex operation or task may only be performed occasionally. Therefore, to expend the power necessary to continuously operate the processor at the highest clock speed required is extremely inefficient from an energy consumption perspective.
To optimize power consumption, heretofore systems have been designed to employ multiple processors operating at different frequencies. U.S. Pat. No. 4,407,288 discloses an implantable heart stimulator controlled by a plurality of processors providing multiple modes of operation for performing various electrical heart stimulation techniques. Each processor is selected by virtue of its design for performing operations of a given type. In one embodiment, two processors are used, one selected for the performance of long term operations, simple in type that consume low power; the other processor is selected for the performance of more complex operations that are shorter in term and consumer more power.
To further reduce power consumption, one or more components may be placed in a sleep mode (low power mode) when not in use. U.S. Pat. No. 5,464,435 discloses a multi-function implantable medical device having a plurality of microprocessors used to perform functionality of varying complexity. Specifically, in one example the functions to be performed continuously are allocated to a dedicated master processor, while advanced functions that may be only periodically required, are allocated among one or more slave processors. With this master/slave arrangement of the parallel processors power consumption is reduced by causing the slave processors to enter a standby or “sleep” mode when not called upon to perform a task thereby consuming a reduced amount of energy than that while in active mode. The master processor upon encountering a task to be allocated or performed by a slave, activates and directs the slave processor to begin executing the desired code. Placing the slave processor in sleep mode, as described in the patented device, still consumes energy, albeit less than that required when the processor is fully powered up (in active mode). In the context of an implantable medical device in a closed system relying on the limited energy drawn from an internal power source, even a reduced amount of energy, expended by the implant while in sleep mode disadvantageously reduces the lifespan of the power source.
It is therefore desirable to optimize power consumption in a device employing multiple electronic components wherein at least one electronic component remains continuously powered on while one or more other electronic components are powered down or off until otherwise energized (powered on) when required to perform a specific task, function or operation. In contrast to the patented sleep mode operation, when in a powered off state the electronic components consume no energy whatsoever until activated to perform a specific task, function or operation.